The town emblem was adopted on Oct 1st 2004 by Ordinance No 3 but there is no flag law.
The white flag has a green and a blue two color town emblem in the center.
The town emblem is stylized a i of Ainan.
It represents the waves of Uwa Sea and an energy of the new town making a leap forward to the future
also the expansion of a vigor and a conformity by a main character the residents.Nozomi Kariyasu, 15 September 2014

According to the
summary of existing emblems during the merger, the emblem was adopted in
July 1968.
It looks to me as though the central part of the emblem is a stylised kanji 本 (本
meanings such as book, origin, in this case a counter for pine trees) of
Ipponmatsu (一本松). That's not what I would expect, but it's what it looks like...
Jonathan Dixon, 09 November 2013

From the
town website through the wayback machine. The emblem is a stylised inital
Latin "M" of Misho. It is in the shape of a bird and a sea animal, and also
expresses a parent and child loving each other. It is a symbol of the
townspeople living in the environment given to them.
According to the
summary of existing emblems during the merger, the emblem was adopted in
April 1991. Jonathan Dixon, 09 November 2013